Generating apparatus for use in removing flammable materials from ducts



Sept. 27, 1966 .J. GUIRE, ET 3,274,700

GENERATING ARA FOR USE R V G FLAMMABLE 6QIVIA'IERIALS FROM DUC OriginalFiled June 21, 19 3 Sheets-Sheet 1 I8 2 1 26 21 6 20 fg j 21 Sept. 27,1966 E. J. MAGUIRE, sR.. ETAL 3,274,700

GENERATING APPARATUS FOR USE IN REMOVING FLAMMABLE MATERIALS FROM DUCTS5 Sheets-Sheet 2 Original Filed June 21. 1960 A IO S p 27, 1966 E. J.MAGUIRE, SR. ETAL 3,274,700

GENERATING APPARATUS FOR USE IN REMOVING FLAMMABLE MATERIALS FROM DUCTSOriginal Filed June 21. 1960 5 Sheets-Sheet 3 United States Patent 1Claim. (Cl. 34--104) This application is a division of our co-pendingapplication Serial Number 37,617 filed June 21, 1960, now abandoned.

This invention relates to apparatus for cleaning ducts, hoods, chimneys,columns, and the like, and more particularly it relates to apparatus forcleaning flammable materials from the surfaces of ducts, hoods, andother surfaces which are not readily accessible, which apparatusutilizes a chlorinated hydrocarbon as the cleaning solvent.

Chlorinated hydrocarbon solvents such as trichloroethylene have beenused extensively in the degreasing of metal workpieces covered withmineral oil and the like. For example, U.S. Patent 2,852,417, issuedSeptember 16, 1958, to Thomas J. Kearney, discloses a method andapparatus for degreasing metal objects wherein the object is firstsprayed with a chlorinated liquid hydrocarbon and is then immersed in abath of liquid chlorinated hydrocarbon while the bath is subjected toultrasonic vibration. Although the techniques of this patent aresuitable for treating small, movable objects, such techniques are notsuitable for cleaning relatively large, stationary objects, such asducts, hoods, and the like.

In restaurants, bakeries, food processing plants, industrial plants, andthe like, it is customary to provide a ventilated hood and duct systemto remove smoke and other foreign matter produced in cooking and bakingoperations. As the smoke passes through the hood and duct, variousforeign matter in the smoke, such as grease, fat, oil, carbon, and thelike, is deposited on the surfaces of the hood and duct. Since suchmaterials are highly flammable, serious fire hazards are created whenthese materials are deposited. Since the hood and duct work are noteasily accessible, fires which occur therein are diflicult to controland may cause serious injury to personnel and great property damagebefore they can be brought under control. Accordingly, in an attempt toprevent such fires, the duct work and hood are frequently cleaned toremove the flammable deposits. Normally, such cleaning must be donemanually and is a tedious, time consuming and costly operation. Addingfurther to the cost of such manual cleaning operation is the loss of thecooking or other equipment during the down time necessary to effect thecleaning. Moreover, because the duct work is often not well ventilated,a serious health hazard may be encountered by the personnel carrying outthe cleaning operation.

It is, therefore, an object of the present invention to provide a novelapparatus which overcomes the disadvantages inherent in the prior arttechniques for cleaning ducts and the like.

Another object of the present invention is to provide a novel apparatuswhich is suitable for cleaning flammable materials such as grease andthe like, from the surfaces of ducts.

Another object of the present invention is to provide an apparatus whichmay be used for extinguishing fires in ducts and the like, in additionto its utility in cleaningprocesses.

3,274,760 Patented Sept. 27, 1966 These and other objects will becomeapparent to those skilled in the art from the description of theinvention which follows.

In the drawings which are attached hereto and form a part hereof, FIGURE1 is a perspective drawing of novel cleaning apparatus of the presentinvention;

FIGURE 2 is a perspective drawing of a cover for the novel cleaningapparatus;

FIGURE 3 is an elevated view of a duct having the novel cleaningapparatus secured thereto;

FIGURE 4 is a detailed plan sectional view taken on the line 44 ofFIGURE 3;

FIGURE 5 is a perspective view of a portable cleaning apparatus securedto the duct; and

FIGURE 6 is an elevational view of the duct with ultrasonic transducersand exhaust fan.

In all of these drawings and the following specification, likecharacters of reference are used to designate corresponding parts.

Pursuant to the above objects, the present invention includes a gasgenerating apparatus, suitable for use in removing flammable materialsfrom the interior surfaces of a stationary duct, which apparatuscomprises a horizon tally disposed trough having endless inner and outervertical-1y disposed wall sections and an endless horizontally disposedbase section, said endless inner wall defining an opening of sufficientcross-sectional area to permit passage of a gas therethrough and saidinner, outer and base sections defining an endless, open-top channeladapted to contain a fire-resistant solvent liquid which is to beconverted to the gaseous state. A heating element is positioned in thelower portion of the trough and located in a generally parallelrelationship with the base section, the heating element, by supplyingheat to the fire resistant solvent liquid in the channel, effectingcontrolled generation of gas therefrom. The apparatus is furtherprovided with a securing means for connecting the trough with a ductdesirably at the lower extremity thereof, so that the trough ispositioned to receive condensate flowing from the duct.

It will be appreciated that for purposes of clarity, the apparatus ofthe present invention is described as applied to conventional hood andduct work, normally used in removing smoke and fumes produced by cookingstoves, ovens and the like. It will be recognized by those skilled inthe art, however, that this apparatus may be employed in cleaning theinterior surfaces of flues, chimneys, stacks, still columns, conduitsand other surfaces that are not easily accesible. Additionally, it is tobe appreciated that the word duct as used throughout the specificationand claim is intended to include ducts, hoods, conduits, chimneys,stacks, still columns, fines, and the like, While the term flammablematerial is intended to include grease, fats, oils, protein, carbon, andother smoke or vapor residues that may be produced by the heating ofcarbonaceous materials during cooking, combustion, evaporation,distillation, and similar operations.

Referring now to the drawing, the novel cleaning apparatus of thepresent invention is comprised of a horizontal trough 10, having anouter perimeter or endless outer wall section 11, a base section B, andan inner perimeter or endless inner wall section 12. The opening createdby the inner perimeter 12 is of suflicient cross sectional area topermit passage of gas therethrough under the usual operation of thestove, oven, or the like. The horizontal trough 10, as shown in thedrawing, is an opentopped channel defined by the inner, outer and basesections and having a rectangular form. It will be recognized by thoseskilled in the art, however, that the trough may have curved sides andmay have a circular form or other form to conform to the duct work whichis to be cleaned. The trough may be constructed of sheet metal, plastic,or other suitable materials of construction.

A heating element is positioned in the area adjacent to the bottom ofthe trough to effect heating of a chlorinated hydrocarbon solvent 14,which is placed in the trough up to the level 15. As shown in thedrawing, this heating element is an electrical heating element 13, whichmay be connected directly to line voltage (not shown) either with orwithout the use of a reostat control (not shown). Although, from thestandpoint of mobility of the cleaning apparatus, electrical heatingelements are preferred, it will be appreciated that other types ofheating elements may be used, as for example, a steam line, hot airline, or the like. Whatever type of heating element is used, it isactivated during the cleaning and/or fire extinguishing operation, toefiect vaporization of the chlorinated hydrocarbon solvent.

If desired, a thermometer 16, or other temperature measuring and sensingdevice may be inserted through the perimeter 11. In addition, thethermometer 16 may be wired, by conventional means, to the electricalheater 13, so as to maintain the desired vaporizing temperature in thechlorinated hydrocarbon solvent.

Chlorinated hydrocarbon solvent 14, is fed into the trough 10, by meansof liquid inlet 17. A sight glass 18 is positioned in the perimeter 11in order to determine the chlorinated hydrocarbon solvent level. Anoverflow line 19 is also positioned in the perimeter 11 to remove excesschlorinated hydrocarbon solvent. The overflow line 19 is located at thepoint of maximum hydrocarbon solvent level which is desired. A dischargeline 20 is positioned in the perimeter 11 at a point at the bottom ofthe trough so as to permit complete drainage of the chlorinatedhydrocarbon solvent from the trough 10. If desired, a strainer (notshown), such as a screen or filter cloth, may be secured to the end ofthe discharge line 20 on the in side of the trough to separate anysuspended solids that may be present in the chlorinated hydrocarbonsolvent which is removed through the discharge line. A valve 21 isprovided in the discharge'line 20 to control the removal of the solvent.

A cover 22 is provided to cover the opening formed by perimeter 12 andthus prevent chlorinated hydrocarbon solvent and flammable materialsfrom dropping through the opening when the cleaning apparatus is inoperation. The top of cover 22 preferably slopes downwardly from thecenter to the outer edge so as to permit drainage of the liquidchlorinated hydrocarbon solvent into the trough 10. The bottom of thecover 22 is, of course, supported by the vertical inner wall ofperimeter 12. During normal operations, i.e., when cooking, baking orthe like, are being carried out, the cover 22 is removed to permit smokeand fumes to be discharged through the duct 23.

Trough 10 is positioned horizontally at the lower extremity of the duct23 and may be secured thereto by bolts 24 and nuts 25, having washers 26which serve to prevent leakage of the solvent from the trough 10. Othermeans suitable to secure or connect the cleaning trough to the duct,such as welding, clamps, or the like, may be employed in place of thebolts and nuts. As shown, the duct 23 is positioned vertically or, itmay be a duct system, at least a portion of which is in a substantiallyvertical position.

An exhuast fan, E, shown in FIGURE 6, is provided at the gas dischargeend of the duct 23 to convey the chlorinated hydrocarbon solvent vaporsfrom the trough 10 throughout the length of the duct when the cleaningapparatus is in operation.

If desired, an ultrasonic transducer, U, may be secured to the outer orinner surfaces of duct 23 to assist in removal of the flammablematerials from the interior surfaces of the duct during the cleaningoperation. In FIG- URE 6, transducers, U, are shown as being secured tothe outer surfaces of the duct 23.

In another modification of the apparatus, rollers, casters, or similarwheeling means, W, as shown in FIGURE 5, may be secured to the end orsides of trough 10 to make the trough portable so that it may be morereadily moved to the area adjacent to the duct. In this modification,cover 22 is placed over the opening formed by perimeter 12 and aflexible duct or curtain type hood, F, as shown in FIGURE 5, isreleasably secured at one end to outer perimeter 11 and at the other endto the bottom of duct "23, thereby permitting vapors generated in trough1G to pass upwardly from the trough past the flexible duct into duct 23,and permitting the resulting condensate to pass downwardly past theflexible duct into trough 10. Thus, the flexible duct functions toprevent migration of the gaseous chlorinated hydrocarbon solvent,thereby insuring its delivery to duct 23, and also serves to convey thecondensed solvent vapors or condensates from duct 23 back into troughIll.

During normal cooking, baking, combustion or other operations whichproduce smoke containing flammable materials, and prior to the cleaningoperation, cover 22 is removed and the trough Ill is preferably empty.When it is necessary to clean the duct, baking, cooking, combustion orthe like operations are discontinued, cover 22 is placed over side 12,valve 21 is closed and a chlorinated hydrocarbon 14 is fed into thetrough 10, through the feed inlet 17, up to the level 15.

Any suitable chlorinated hydrocarbon solvent which is capable ofdissolving flammable materials from the surface of the duct may beemployed. Exemplary of such solvents are trichloroethylene,tetrachloroethylene, tetrachloroethane, trichloroethane,methylenechloride, carbon tetrachloride, and mixtures thereof. Of thesetrichloroethylene is the preferred chlorinated hydrocarbon solvent and,hence, hereinafter primary reference will be made to this material.

After the trichloroethylene has been introduced into the trough 10, theelectrical heating element 13 is turned on and sufiicient heat issupplied to effect vaporization of the chlorinated hydrocarbon solvent.The fan may also be activated so as to convey the vapors throughout thelength of the duct which is to be cleaned. As the vapors contact theinterior surfaces of the duct, the vapors condense and dissolvesubstantially all of the flammable materials adhering to the interiorsurfaces of the duct. When an ultrasonic transducer is employed, removalof the flamma ble material from the interior surfaces of the duct ismaterially aided. Insoluble materials such as carbon particles whichadhere to grease and other soluble flammable materials on the interiorsurface of the duct are suspended in the condensed chlorinatedhydrocarbon solvent. The solvent, containing dissolved flammablematerials as well as the suspended insoluble particles flows downwardlyon the interior surf-aces of the duct and passes into the trough, wherefurther evaporation of the solvent is eifected and the cycle isrepeated.

Water, which may also be present in the duct, also condenses and isconveyed to the trough with the chlorinated hydrocarbon solvent. Toprevent contamination of the solvent with water, a liquid silicone,preferably having a specific gravity between 1.0 and about 1.05, may beadded in small amounts to the chlorinated hydrocarbon solvent. Thesilicone floats on top of the chlorinated solvent and any waterintroduced into the trough then floats on top of the silicone withoutcontaminating the chlorinated hydrocarbon solvent.

If desired, during the cleaning operation, an aromatic compound having apleasant odor, such as peppermint or the like, may be admixed with thesolvent or sprayed into the duct to prevent odors, such as pungentchlorinated hydrocarbon solvent odors, from passing throughout thekitchen, bakery, or the like. Additionally, other cleaning compounds mayalso be used in combination with the chlorinated hydrocarbon solvent.For example,

ammonia may be released into the duct to be cleaned simultaneously withthe generation of the chlorinated hydrocarbon solvent vapor, to assistin removing flammable materials from the interior surfaces of the duct.

After the interior surfaces of the duct have been cleaned, the heatingelement is turned off and the major amount of the chlorinatedhydrocarbon solvent vapors remaining in the duct are permitted tocondense and flow into the trough. The temperature of the interiorsurfaces of the duct under ambient conditions is generally below theboiling or condensation temperature of the chlorinated hydrocarbonsolvent and is, thus, sufficient to cause condensation of a majorportion of the solvent vapors passing through the duct. If desired,however, auxiliary cooling means, such as cooling coils, may be employedto aid in this condensation. When the condensation is sufiicientlycomplete, the cover 22 is re moved andthe liquid chlorinated hydrocarbonsolvent in the trough, either with or without added silicone, is removedthrough the discharge line by opening valve 21. The solvent is collectedin a suitable container and stored until it is needed for the nextcleaning operation. Where the water layer is present on top of thesilicone and chlorinated hydrocarbon solvent, the valve 20 will beclosed after removing substantially all of the hydrocarbon solvent fromthe trough. The water layer will then be removed through the dischargeline and discarded. The fan, E, in the duct, may be utilized to removeany remaining chlorinated hydrocarbon solvent vapors from the duct,after which norm-a1 baking, cooking or other operations can be resumed.

By using the cleaning apparatus of the present invention, the cleaningof flammable deposits from the interior of ducts and the like isaccomplished much more easily and quickly than has been possible usingprior art cleaning techniques, which techniques have largely involvedmanual cleaning operations. By thus eliminating much of the hand ormanual labor previously required in such cleaning operations and alsogreatly reducing the down time of the cooking, baking or otherequipment, there is realized considerable savings both in labor costsand in increased operating time of the equipment.

While, as has been described hereina'bove, an important function of thepresent apparatus is in cleaning flammable material from ducts, theapparatus may also be employed to extinguish fires which may start inducts containing flammable materials. In the event of a fire in theduct, the chlorinated hydrocarbon solvent is added to the trough of theapparatus, the heating element is activated and the resultingchiorinatedhydrocarbon vapors pass into the duct and quickly extinguishthe flames,

6 thereby eliminating or at least minimizing a serious fire hazard.

While there have been described various embodiments of the invention,the structures and methods described are not intended to be understoodas limiting the scope of the invention, as it is realized that changestherewit-hin are possible, and it is intended that each element recitedin the following claim is to be understood as referring to allequivalent elements for accomplishing substantially the same results insubstantially the same or equivalent manner, it being intended to coverthe invention broadly in whatever form its principles may be utilized.

What is claimed is:

A portable gas-generating apparatus useful in removing flammablematerials from the interior surfaces of a stationary duct, whichapparatus comprises a horizontally disposed trough having endless innerand outer substantially vertically disposed wall sections and an endlesssubstantially horizontally disposed base section, said endless innerwall defining an opening of sufficient crosssectional area to permitpassage of gas therethrough and said inner, outer and base sectionsdefining an endless open-topped channed adapted to contain afire-resistant solvent liquid which is to be converted to the gaseousstate, an electrical heating element positioned in the lower portion ofthe trough and located in a generally parallel relationship with thebase section, said heating element, upon activation, effectingcontrolled generation of solvent gas from the fire-resistant solventliquid contained in the open-topped channel, a releasable flexible ductsecured at its upper portion to the lower peripheral edge of thestationary duct and at its lower portion to the outer wall section ofthe trough, and means provided on the trough to allow rolling movementthereof.

References Cited by the Examiner UNITED STATES PATENTS 2,029,781 2/ 1936McLean 1 34168 X 2,393,957 2/1946 Baum-gartner --115 2,483,993 10/ 1 949Becker. 2,645,095 7/ 1953 Ploeger 134169 X 3,0l-1,924 12/1961 Rand134-105 X 3,049,450 8/1962 Koons et al. 134105 X 3,055,285 9/ 196 2Gaylord 98- 1 15 FOREIGN PATENTS 142,323 9/ 1953 Sweden.

CHARLES A. WILLMUTH, Primary Examiner.

R. L. BLEUTGE, Assistant Examiner.

